SHANGHAI (Reuters) - China’s environmental crackdown is the “biggest uncertainty” facing the nation’s copper smelters, as the government steps up inspections and stiffens emissions control standards, an executive at Jiangxi Copper Co Ltd said on Wednesday.

A worker loads copper cathodes into a warehouse near Yangshan Deep Water Port, south of Shanghai March 23, 2012. REUTERS/Carlos Barria/File Photo

“Producers risk being shut down. Supervision teams are everywhere,” Yuneng Wu, vice president of the state-owned company, which is the country’s top integrated copper producer, said at the Asia Copper Conference in Shanghai.

China’s major smelters have eliminated outdated technology and upgraded equipment as part of the government’s push to make the industry more efficient and reduce pollution, he said.

But this year the emissions requirements were strengthened by 50 percent, requiring companies to install more environmental protection equipment.